Apparatus for sorting postal packets



Sept. 9, 1952 J."'F. DOUST APPARATUS FOR SORTING POSTAL PACKETS Filed Jan. 12, 1948 2 SHEETS-SHEET l 4 //VVE/V James frer/er/rk Dot/s7;

Sept. 9, 1952 J. F. DOUST APPARATUS FOR SORTING POSTAL PACKETS 2 SHEETS--SHEET 2 Filed Jan. 12, 1948 INV E NTOR ATTORNEY Patented Sept. 9, 1952 OFFICE APPARATUS FOR SORTING POSTAL PACKETS James Frederick Doust, London, England Application J amiary 12-, 1948, Serial No. 1,781 In Great Britain December 31, 1946 Section 1, Public Law 690, August a, 1946 Patent expires December 31, 1966 6 Claims.

It is known in sorting postal packets for an operator to cause any particular packet to be deposited in one of a number of boxes forming an endless conveyor each of which is provided with trips which the operator sets by a code according to the destination of the packet, the trips so set causing the box to open above the chute or cornpartment appropriate to the destination in question. This" method has the drawback that the operations of converting the destination into a code and of sorting the packets are combined in a single machine. By the present invention, the operations of coding and sorting are dissociated from each other, thus enabling both to be carried out with greater efiiciency, and also enabling the scrtmgtc he performed at any convenient locathan which" may, if desired, be remote from the coding omce. Y

The invention consists in a method of sorting postal packets which comprises applying to each packet a set of substantially invisible or transparent marks of fluorescent material of which the position, number and/or emitted wave band is related to the destination of the packet by a code, and conveying the p'ackets so marked to sorting means'oi' to a succession of sorting means comprising; or each comprising, means for projecting exciting radiation on the marks, photoelectric i'orde'tec'tihg the emitted radiation, and a code reading device adapted to be operated by the output the said photoelectric means so as tbc'entmi a directing device Ior'sorting the packets cocci-chic to their destinations.

The term fluorescent material" as used herein means a material which, when subjected to radiation capable or exciting it, fluoresces to a substantially greater extent than the envelope or Wrapping to which it is applied.

"In an advantageousapplication or the inventicmthe set of marksapplied to each packet comprises a number of series of marks, each-series of mhrks being related to one item of the address on the' packe't, and the packets are then contc sorting means which sort them into batches according to the first item of theaddr'ess. Each batch. is then conveyed to sub-sorting which sort the articles according to the second item of the address, and so on. 'ihus, for example,- the packets'may besorted by the first sorting-meansaccordingto main towns or postal regions. Each batch is" then conveyed to its appropriate regional ofilcewhereit is. fed .to the second sorting means which sorts the packets into postal sub-regions, No-ffurther coding. is n at the regional oflice since both the reion and the sub-region have been coded at the original coding ofiice. This process can be continued until each packet is sorted to its final destination, but only if the marks are applied to the packet by the consignor, who would have to be aware of the code appropriate to the full addresses of a number of individual consignees. To enable the consignor to apply the code, coding machines may be provided for use by the general public, for example in private premises or kiosks. Such machines may be coin-freed, in which case they may be adapted to apply a franking mark to the packet in addition to the code.

The marks may be of any convenient shape, for example rectangles, circles or dashes, and any convenient code may be used. Where only one type of fluorescent material is used, the code is in binary scale, that is consisting of combinations of marks and spaces.

The packets may preferably be scanned by a fixed source of light and a fixed photoelectric cell while they are in motion from the stack of coded packets to the directing device. In this case an advantageous method of sampling the output of the photoelectric cell approximately at the centre of each code mark or space consists in arranging that the code reading device is triggered into operation by the difierentiated output of a photoelectric cell illuminated by a beam of light which is increased or decreased in intensity in steps by the advancing envelope in such a manner that an increase or decrease occurs each time the centre, or approximately the centre, of a code mark or space passes the scanning position.

The invention also includes apparatus for carrying out the method described in the preceding paragraph which comprises means for conveying a succession of postal packets througha scanning position, means for projecting a beam of exciting radiation on the code marks on the packets at the scanning position, a scanning photoelectric cell arranged to receive fluorescent radiation emitted by the code marks, a. code-reading device adapted; when'tri'ggered, to be operated by the output of the scanning photoelectric cell, and a triggering photoelectric cell which is. connected decreases or increases in; stepseach time the centre, or approximately the centre, of a code mark or space passes the scanning position.

The source of exciting radiation may preferably be intermittent in order that the output from the photoelectric cell may be alternating, and therefore more easy to amplify. The intermittent radiation may be furnished by a lamp of the gas discharge type fed with alternating current, or by a continuous source of radiation having a mechanical interruptor.

Suitable fluorescent materials are, for example, the sodium salt of lt lJ-di-(para-aminobenzoylamino) stilbene 2 :2 disulphonic acid, that known by the trade name Primuline (Colour Index No. 812), fluorescein, and eosin. These materials fiuoresce under ultra-violet radiation, the colour of the emitted radiation being blue in the case of the sodium salt of 4: l'-di-(paraaminobenzoylamino) -stilbene 2 :2 disulphonic acid, blue-white in the case of Primuline, green in the case of fluorescein, and yellow in the case of eosin. The colours in daylight of these materials are, respectively, colourless, primrose yellow, yellow, and pink. The materials are effective in extremely thin layers, obtainable, for example, by applying them to the packet in the form of 0.1 per cent aqueous solutions, so that the applied marks are either invisible (in the case of the sodium salt of 4:4'-di-(para-aminobenzoylamino) -stilbene 2:2 disulp-honic acid) or faintly coloured transparencies in the case of Primuline, fluorescein and eosin.

A suitable source of radiation, is, for example, a mercury vapour discharge lamp, for example a 125-watt medium-pressure lamp enclosed in a bulb of filter glass which transmits only the ultra-violet radiation. Practically all the radiation emitted from a lamp of this kind has a wavelength in the region of 3650 Angstrom units.

Most grades of paper used for stationery fluoresce to a small extent, but their fluorescence is negligible in comparison with that of the fluorescent materials described above. Thus, for eX- ample, the fluorescence of these materials, when exposed to radiation of wave-length 3650 Angstrom units, is of the order of 50 times that of an ordinary white envelope when exposed to the same radiation.

The invention is illustrated by way of example by the accompanying drawings, in which Fig. 1 represents an envelope bearing marks of fluorescent material,

Fig. 2 is a diagrammatic. view of the means for scanning the marks. andsorting the letters,

Fig. 3 is a graph of theoutput of the scanning photoelectric cell,

Fig. 4 is a schematic diagram illustrating the operation of the system.

Referring to the drawings, the marks I of fiuorescent material on the envelope ii) are combined with blank spaces 2 soas to represent the destination of the letter in a binary code. Each of the rectangles l and 2 is;des'cribed herein as a code on a triggering photocell 6.

l An ultra-violet lamp emits a beam of radiation capable of exciting the fluorescent material, and the beam is focussed on the envelope It] by a compound lens 8. Some of the radiation emitted by the fluorescent marks falls on the photocell 9, the output of which is used to operate code-reading means described below.

Situated adjacent to the belt II are a number of diverters M. In the apparatus described, the number of diverters is assumed to be sixteen, corresponding with the four code areas shown in Fig. l but the number of diverters could be increased to any desired figure by suitably increasing the number of code areas making up the code on the envelope. Each diverter comprises an electro-magnet consisting of coils [5, a yoke l6 and a pole piece H, and an armature l8 pivoted at l9 and carrying a diverter blade 20. As described below, when any given envelope has been scanned, the coils 20 of one of the diverters appropriate to the fluorescent code on that envelope are energised through connections not shown in Fig. 2. The armature l8 and blade 20 of that diverter then turn in the clockwise direction, and when the envelope in question meets the operated blade 20, it is diverted thereby from the belt ll into a sorting box 2|. In Fig. 2, the second diverter blade from the right is shown in the operated position. Upon deenergisation of the coils 15 through the agency of re-setting signals described below, the blade 28 is returned to its normal position by a spring 30.

Fig. 3 is a graph, not drawn to scale, illustrating the voltage output from the photocell 9 as the code passes the scanning position, the lamp 1 being run on an alternating current of frequency 1600 cycles per second. The ratio of the output corresponding with the fluorescent marks to the background output is of the order of 30 decibels, if the type of photocell is correctly chosen.

. The object of the mask 4 and triggering photocell 6 is to provide a timing system, which is independent of the speed of the envelope, for triggering the code-reading means as described below as the centre of each mark or space I or 2 passes the scanning position. As the envelope advances, it covers each of the slots of the mask 4 insuccession. The code is placed in a standard position on each envelope (shown as the bottom left corner) and the mask 4 isso arranged that as the centre of the first mark or space passes the scanning position, the leading edge of the envelope covers the first slot of the mask 4, as the centre of the second mark or space passes the scanning position, the leading edge of theenvelope covers the second slot, and so on. The light falling on the triggering photocell 6 I is thus reduced in intensity "by one step each time the centre of a mark or spacepasses thescanning position. v I

The output of the photocell 6 is passed into a diflerentiating circuit theoutput ofwhichis used to trigger the code reading'device; The latter .is thus operated by the output of the photocell 9 at the centre of each mark or space, which is independent of anyindefiniteness or malformation at the edges of the marks. I

It will be appreciated that, the slotted mask 4 could be arranged, in advance of the scanning position, so that asthe envelope advanced it'would uncover the slots successively, thus increasi'ngthe intensity of illumination of the photocell- G in steps instead of decreasing it.- In this case the code would be placed in'a predetermined position relatively to the trailing instead of the leadg the mask 4.

mg 'edge'of the envem e- To avoid repetition ofclaims; therefore, where one of these arrangements is Specified in any of the appended claims, the other is to be understood as an equivalent t n i As above noted," the details of the particular of codereadingdeviceyand the particular dtailsof the triggering circuit therefor, formnd part of the present invention, and these old elements, per se, maybe of any known form, the invention hereinresiding in the combining of the binary'response Of the code reading photocell 9 with the differentiated action of the triggering photocell 6 to render the permutation 'of the code readable and translatable to energize one of a number of director actuating circuits determined by the permutations of the code, while the coded letter is moving and independently of its speed. In the U. S. patent to Ayres-ct al. No. 2,056,382 issued October '6, 1936, for example, six mark and space elements are applied to the letter in two rows each having" three code areas therein and each arranged transversely of the direction 'of movement of the envelope. In that system the rowsof code areas are scanned by apertures in a fixedly positioned rotating disc and the letter has to'be held stationary during the scanning. That system further includes a code reading device having a triggered relay selector comprising a rotary switch (designated by Ayres et al.) mechanically triggered or driven in synchronism with the rotating disc (16 therein), for sequentially connecting thecode reading photocell to and disconnecting it from six: holding-relay circuits (23 therein), of a binary permutation switch (3l therein) there'b'eing one holding relay for eachcode area. The energizing or non-energizing'of each of the six holding relays by the code reading photocell (designated l'l in Ayres et al.) inflresponse" to the presence of' a spacefor mark in corresponding code areaon the envelope, occurrin as the arm of the rotary switch (2% therein) passes acrossitscontacts, establishes a circuit froma sourceof power through the banks of permutation contactsioithe permutation switch (303l therein) and energizes that single one of thirty-two director controlling circuits (32 therein) corresponding 'to the permutations of marks and spaces in the 6-element binary code area on the letter.

Such a system may be employed in practicing the present invention, in which case 1) the photocell ll of Ayres et al., corresponding to the code-reading photocell 9 in the present disclosure, may be located to scan the single row of binary code elements moving therepast as indicated in Fig. 2, herein, and (2) the triggered switch 20 of Ayres et al. may be moved across its contacts to momentarily connect the cell 9' to the respective holding-relay circuits, not by driving it synchronously with a scanning disc as in Ayres et al., but by stepping it in response to each change in output of the photocell 6 produced by the advance of the leading edge of the envelope across The differentiating circuit hereinabove mentioned, well known per se, as its name implies is a circuit that produces a constant output as long as its input remains steady at any level, and which increases its output only while the input is changing. An ordinary transformer is one example, since with a D. C. input it produces apulse of output during each period of change of input, and such output pulses may be employed to trigger the stepping of the switch 20 of the Ayres et a1. system as in the stepping of any known form of selector or" stepping switch,

one: example of which is shown per se' in the'patent to 'Kermode et al. No; 1,985,035, dated Decem-" ber"l'8,1934 I r 1 Accordingly, with the triggering of this known form of permutation codereadingd'evice by the dififehtiat'edoutput or the triggeringphotocell 6' as herein disclosed, the operation of the system may take place in the manner indicated in the schematicdiagram, Fig. 4-,- namely: 1

(A) As the-envelope, with mark and space coding positioned in definite spaced relation to its leadingedge, enters the conveyor,- the first cod ing element I (Fig; 1) comes into position to be energized by' source 7' (Fig. 1) and if marked, illuminates c'od'e' reading photocell' 9. (B) As the c'e'ntrd'po'sit'ion for such illumination is'rea'chedthe leading edge of the envelope closes the-first epenmg m the mask 4 (Fig. 2) and the output of the trig-gerin'g' photocell 6' is reduced one step, as at a. This reduction in output being fed to a' conventional diiierentiating circuit (C) produces a differentiated output or pulse of energy, as b, which triggers or renders transiently responsive to the output of code reading tube 9-the actuating circuit C of a first holding relay D correspondingto the first code element being read by photocell S. As in the patent toAyres et al., for pur poses of illustration the transient energizationor non energiza'tion of holding relay D may'effect or maintain the closing ofcertain groups-of con tacts in the permutation switch-bank E, depending onlwhether or not the photocelliiis energized by the code elements'canned.

As the'second, third and fourth code areas l 2 each become centered with the code' reading photocell 9, the leading edge of the envelope repeatedly reduces the output of triggering photocell 6, and the difierentiator C. repeatedly pulses the triggering circuit, thus triggering or tran sientlyconnec'ting the output derived from the reading of the code areas by the photocell 9 to the respective conductive paths C C C leading tothe stick relay D D or D corresponding to the respectivecode area. When the presence of a mark" or space in each ofthe codeareashas thus been registered by energization or -nonenergization of the holding relays D D of the conventional permutation switch E, that output circuit of the switch E, pre-determined by the permutations of marks and spaces thus registered is completed, and in turn operates that one of the directors I4 predetermined to correspond to the code combination appearing on the envelope.

As will be appreciated by those skilled in the art, a code reading device may comprise either electro-mechanical stepping switches and relays, or electronic equivalents thereof cooperating with pulse actuable triggers of any type; and may comprise directly selected output circuits or output circuits selected in any other manner, depending on the system used, and such details form no part of the present invention, which is not limited to the use of any particular type of code reading devices, triggering devices, or diverters, as the invention resides in the new coordination of such means, and not in the details of the components, per se, which are herein illustrated merelyfor the purpose of aiding in the understanding of the invention.

I claim:

1. In an improved apparatus for sorting postal series of several coding areas, the series of coding areas on each article being linearly arranged and spaced sequentially in a predetermined direction, code reading means triggerable to read selectively the coding in each of said several areas at distinct time intervals, triggering means for so triggering said code reading means, said code reading means including photoelectric mark-sensing means responsive to the presence or absence of marks in the respective ones of said several areas for operating said code reading means in its correspondingly triggered condition, said improved system being particularly characterized in that it includes conveying means for continuously moving the articles in a predetermined direction past the mark sensing means, and in that the triggering means for the code reading means is actuated by movement of the article by the conveying means in said predetermined direction for triggering said code reading means as such movement sequentially exhibits each of the respective ones of said several coding areas to said mark sensing means, and in that the triggering means comprises photocell means and light source means producing a series of light beams corresponding to the number of coding areas employed, said light beams being projected to said photo-cell means across the path through which said article is moved and being spaced longitudinally to be sequentially interrupted by the article as the article moves to exhibit sequential ones of said series of coding areas to said mark-sensing means, thereby to alter the output of said photo-cell means for triggering said code reading means.

: 2. An improved system for sorting postal articles according to claim 1, particularly characterized in that the triggering means comprises a single photo-cell means and a mask having a series of apertures therein through which said light beamsproject to said photo-cell means, said apertures being sequentially spaced on centers by distances equal to the spacings of the coding positions on the articles, and said mask being located so that the moving article cumulatively covers said apertures one at a time for each of the coding areas it exhibits to said mark-sensing means. I

3. An improved system for sorting postal articles according to claim 2, particularly characterized in that said apertures are relatively narrow compared to the length of each of said coding areas in the predetermined direction of movement of the article, and in that said mask is positioned so that the covering of each aperture by the article synchronizes approximately with the centering of the corresponding area with respect to the photo-electric mark sensing means.

4. A system for sorting postal articles according to claim 3, in which said apertures are in the form of slots disposed parallel to the leading and trailing edges of postal articles being moved by said conveying means;

5. A system according to claim 1, in which said marks comprise fluorescent material, and in which said system comprises means for projecting exciting radiation on said coding areas as they are exhibited to the mark sensing means, and said mark sensing means comprises photo-cell means responsive to the fluorescence of said marks under said exciting radiation, said marks being substantially invisible under ordinary light.

6. A system according to claim 5, in which the means for projecting the exciting radiation operates to project said radiation intermittently so that said mark sensing photo-cell produces an amplifiable output.

JAMES FREDERICK DCUST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,979,722 Zworykin Nov. 6, 1934 1,985,035 Kermode Dec. 18,1934 2,020,925 Young Nov. 12, 1935 2,056,382 Ayres Oct. 6, 1936 2,231,494 Dickinson Feb. 11, 1941 2,280,948 Gulliksen Apr. 28, 1942 2,297,939 Campbell Oct. 6, 1942 FOREIGN PATENTS Number Country Date 294,575 Great Britain Sept. 19,1928 

